This study presents a video analysis method for assembly factories. In recent years, there has been an increasing demand to collect manufacturing data in the manufacturing industry. While visualizing manufacturing data in real time to analyze practical manual work has not yet been realized, technologies for data collection, analysis and visualization have made progress using many kinds of machines and sensors. The introduction of various sensors and machines has resulted in changes in processes for visualizing the collection of manufacturing data in real time and analyzing it, as well as the collection and analysis of data. While difficult to do manually, the real-time monitoring of production data can help to quickly respond to problems, investigate causes, and improve operations. Therefore the authors propose a work analysis method that uses videos to analyze hand movement and position and product position. As a result, an analysis accuracy of 99.3% is obtained when studying standardized work in an ideal capture environment, and the cause of the reduction in accuracy is clarified.